Microwave polarization switch



June 23, 1970 E. P. AUGUSTIN 3,517,341

MICROWAVE POLARIZATION SWITCH Filed Sept. 16, 1968 Fig.2

' 10s I 9o I00 no as 8 0 I02 I VIINVENTOR. H93 EUGENE P. 'AUGUSTIN United States Patent O 3,517,341 MICROWAVE POLARIZATION SWITCH Eugene P. Augustin, San Diego, Calif., assignor to Teledyne, Inc., Hawthorne, Calif., a corporation of Delaware Filed Sept. 16, 1968, Ser. No. 759,866 Int. Cl. H01p 1/16, 1/06, /08

U.S. Cl. 33321 6 Claims ABSTRACT OF THE DISCLOSURE BACKGROUND OF THE INVENTION The present invention relates to microwave apparatus and waveguides and specifically to a microwave polarization switch. In waveguide structures rotary couplings have been used for scanning motions, or to rotate the plane of polarization of the microwave energy. Such couplings have included the type having a stack of similar elements each with a slot, usually rectangular, corresponding to the waveguide cross section, the elements being coupled in some manner to rotate in successively stepped relation by torque action. Elaborate gearing and interconnecting mechanisms have been used to ensure that the effective plane of polarization is rotated in constant increments through the successive slots. In most instances the coupling is operated by an external motor or other actuating means, making the assembly undesirably bulky.

SUMMARY OF THE INVENTION The polarization switch described herein is self-contained, with internal drive means, in a generally cylindrical container no larger in diameter than the conventional waveguide end connection to be coupled to the unit. The driven portion is a transition section in which the waveguide opening changes in steps from a rectangular input to a circular output opening, from which any polarization can be propagated. A single impedance matching separator mechanically couples the transition section to the fixed rectangular input in correct stepped relation, and the transition section is made self-returning to a specific orientation by an integral cam arrangement.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is an end elevation view of the complete unit, as taken from the outlet end;

FIG. 2 is a sectional view taken on line 22 of FIG. 1;

FIG. 3 is a sectional view taken on line 33 of FIG. 2; and

FIG. 4 is a sectional view taken on line 4-4 of FIG. 2.

Similar characters of reference indicate similar or identical elements and portions throughout the specification and throughout the views of the drawing.

DESCRIPTION OF THE PREFERRED EMBODIMENT The switch is contained in a generally cylindrical casing having an input end 12 and an output end 14. Inset into the input end 12 is an end plate 16 sealed to the inside of the casing by an O-ring 18 and held by set 3,517,341 Patented June 23, 1970 ice screws 20, or similar means. End plate 16 has a rectangular input waveguide opening 22 corresponding to the cross section of the conventional input waveguide, not shown, whose standardized connecting flange attaches to the end 12. A short distance from end plate 16 the casing has a diametrical wall 24 with a central circular opening 26, the wall having a socket portion 28 concentric with said opening to hold a ball bearing 30, or similar freely rotatable bearing.

Axially rotatably mounted in bearing 30 is a transition section 32, comprising a cylindrical sleeve 34 with an enlarged portion 36 which fits securely into the bearing, and a radially extending flange 38 on the end adjacent input. At the flanged end the transition section 32 has a rectangular opening 40 corresponding to input opening 22, while the sleeve portion has a circular axial opening 42. In the enlarged portion 36 is a transition opening 44 which is wider than opening 40 and has roundedends to provide an intermediate step between the rectangular and circular configurations.

Axially mounted between transition section 32 and the end plate 16 is a thick disc-like separator 46 having a rectangular opening 48 corresponding to inlet opening 22. End plate 16 has a socket 50 and transition section 32 has a corresponding socket 52 into which the ends of separator 46 are recessed. The separator is supported by circumferentially spaced rollers 54 rotatably mounted on radial pins 56 fixed in the separator, three rollers being shown as an example. Rollers 54 ride on the inner face of end plate 16 and on the end face of flange 38, holding the separator in coaxial, noncontacting relation therebetween. The inner faces of end plate 16 and separator 46 have circular slots 58 and 60, respectively, to act as choke joints, the technique being well known in waveguide joint structures.

Secured in the output end 14 is an end plate 62 having a central opening 64 coaxial with and corresponding to opening 42 in the transition element, the outer face of said end plate having concentric slots 66 and 68 to form a choke joint. Inwardly of the end plate 62 is a spacer ring 70 sealed to the inside of casing 10 by an O-ring 72. The spacer ring has a radially inwardly extending wall 74 with a central opening 76 to clear the sleeve 34, said wall being axially spaced from end plate 62 to leave an annular channel 78. The end structure thus forms a non-contacting choke junction between the transition element and the output.

Secured between spacer ring 70 and wall 24 is the stator 80 of a torque motor 82, the rotor 84 of which is fixed on sleeve 34. Torque motor 82 may be of any suitable type, such as a conventional electromagnetic motor, a torsional solenoid, a magnetic impulse arrangement, or any other means capable of providing a controlled rotation of the transition section. Consequently, the sectioned portions of the motor in FIG. 2 are intended to be representative only. Since the conventional end flange connections of waveguides are circular and considerably larger than the waveguide cross section, the casing 10 is conveniently made that diameter. Due to the stepped structure of the transition section, this leaves ample space within the casing to enclose the necessary drive means.

A portion of flange 38 is shaped to form a cardioid cam 86, shown as extending about 45 degrees on each side of a central low point 88 in FIG. 3. The actual extent and configuration of the cam will depend on the required rotational limits of the transition section, the arrangement shown allowing for a travel of 90 degrees within the functional range of the cam. Extending radially from casing 10 in the plane of flange 38 is a cylindrical barrel 90, having a bore 92 in which is a radially slidable plunger 94. The plunger is held against rotation by ribs 96 riding in grooves 98 in the bore 92. At the inner end of plunger 94 is a fork 100 in which is a freely rotatable cam following roller 102. Plunger 94 is biased inwardly by a compression spring 104 held in place by an end cap 106, which is threaded or otherwise secured on the outer end of barrel 90. Roller 102 thus exerts a pressure on earn 86 and provides a self-centering action of the transition section by tending to return to the low point 88.

The orientation of the transition section in neutral position relative to input opening 22 will depend on the particular use of the switch. In FIG. 2 the input opening 22 is indicated as being at 45 degrees to the plane of the section, the openings 40 and 48 being similarly oriented so that all three rectangular openings are aligned. This position is also shown in FIGS. 1 and 3. In FIG. 4, the transition section is shown rotated so that opening 40 is offset 45 degrees from input opening 22. The coupling of separator 46 between the transition section and fixed end plate 16, by the rollers 54, causes the separator to rotate in the same direction and at half the rate of the transition section, so that the opening 48, as shown in FIG. 4, has half the angular offset of opening 40, relative to input opening 22. The polarization of microwave energy is thus rotated in steps to the selected orientation. By suitable application of power to motor 82 the polarization can be varied as necessary.

When the motor '82 is not energized, the cam action will return the transition section, together with the separator, to neutral position. Since the range of rotation of polarization can vary, no limiting means have been shown. However, it would be a simple matter to incorporate stops to limit the motion of the transition section to specific angles of orientation. In any position the structure provides impedance matched transition from a rectangular input to a circular output waveguide, from which any orientation of polarization is effectively propagated.

It is understood that minor variation from the form of the invention disclosed herein may be made without departure from the spirit and scope of the invention, and that the specification and drawing are to be considered as merely illustrative rather than limiting.

What I claim is:

1. A microwave polarization switch, comprising:

a casing having an input end portion with a rectangular input waveguide opening therein and an output end portion with a circular output waveguide opening therein;

a transition section rotatably mounted in said casing coaxially between said input and output openings;

said transition section having a rectangular opening at the input end thereof corresponding to said input opening, a circular opening at the output end thereof corresponding said said output opening, and a transition opening intermediate the ends slightly longer than said input opening and with rounded ends to provide a geometrical transition from rectangular to circular configuration;

and means to rotate said transition section to selected orientations relative to said input opening.

2. The structure of claim 1, wherein said last mentioned means is a torque motor within said casing and coupled to said transition section.

3. The structure of claim 1 and including at least one disc-like separator having a rectangular opening corresponding to said input opening, said separator being coaxially mounted between said transition section and said input end portion and being mechanically coupled thereto to rotate at a fraction of the rate of said transition section in the same direction therewith.

4. A microwave polarization switch, comprising:

a casing having an input end portion with a rectangular input Waveguide opening therein and an output end portion With a circular output waveguide opening therein;

a transition section rotatably mounted in said casing coaxially between said input and output openings;

said transition section having a rectangular opening at the input end thereof corresponding to said input opening, a circular opening at the output end thereof corresponding to said input opening, and a transition opening intermediate the ends shaped to provide a geometrical transition from rectangular to circular configuration;

means to rotate said transition section to selected orientations relative to said input opening;

at least one disc-like separator having a rectangular opening corresponding to said input opening, said separator being coaxially mounted between said transition section and said input end portion and being mechanically coupled thereto to rotate at a fraction of the rate of said transition section in the same direction therewith;

said separator having circumferentially spaced rollers rotatable about substantially radial axes thereon and in rolling contact with opposed faces of said transition section and said input end portion.

5. A microwave polarization switch, comprising:

a casing having an input end portion with a rectangular input waveguide opening therein and an output end portion with a circular output waveguide opening therein;

a transition section rotatably mounted in said casing coaxially between said input and output openings;

said transition section having a rectangular opening at the input end thereof corresponding to said input opening, a circular opening at the output end thereof corresponding to said input opening, and a transition opening intermediate the ends shaped to provide a geometrical transition from rectangular to circular configuration;

means to rotate said transition section to selected orientations relative to said input opening;

and means biasing said transition section to a predetermined neutral position of orientation relative to said input opening.

6. The structure of claim 5, wherein said centering means includes a cam integral with said transition section, and a cam follower mounted in said casing and biased into engagement with said cam.

References Cited UNITED STATES PATENTS 2,859,412 11/1958 Mari 333-98 X 2,985,850 5/1961 Crawford et al. 3332l X 3,001,159 9/1961 Hilsinger 33398 HERMAN KARL SAALBACH, Primary Examiner M. NUSSBAUM, Assistant Examiner US. Cl. X. R. 

